Forward and reverse friction gear transmission



Oct. 10, 1950 CARL-ERIK sRAN ws-r 2,524,905 FoRymRo AND REVERSE FRICTION GEAR TRANSMISSION 5 Filed Jan. 22, 1946 T q- A? A? k VWWW /A I Z INVENTOR BY I i W M ATTORNEY Patented a. 10, 1950 FORWARD AND REVERSE FRICTION GEAR TRANSMISSION Garl-Erik Granqvist, Lidingo', Sweden, assignor to Svenska Aktiebolaget Gasaccumulator, Lidingo, Sweden, a corporation of Sweden Application January 22, 1946, Serial No. 642,701 In Sweden January 25, 1945 The present invention refers to an engageable and disengageable friction gearing, primarily intended to be employed as a servo-motor in remote control systems but applicable also to all kinds of other different purposes.

When a friction gearing is to be used as a servo-motor in a remote control system, the object is to transfer motion from a usually continuously rotating shaft to the shaft to be adjusted. The accuracy of the remote control depends upon the rapidity with which the servo-motor operates, and when friction couplings or friction. gearings have been employed between a continuously.

rotating shaft and the shaft to be adjusted, the

object has primarily been to obtaina very-rapid adjustment. If one shaft rotates continuously with its full number of revolutions and if the adjusted shaft and the parts connected with it have a sufficiently small mass, a very swift motion and particularly a very swift acceleration of the motion could be effected. In practice, however, it has proved impossible fully to attain the advantages aimed at for th reason that the closing time of the friction coupling has been too long.

The present invention refers to a friction gearing whichis intended to connect a preferably continuously rotating, driving shaft witha shaft intermittently driven in one direction or the other and which is provided with balls or rollers be understood by reference to the ensuing portion of this specification and by the accompanying drawings forming a part hereof which disclose by way of example but without limitation suitable forms of apparatus for carrying the invention into effect. I

In the drawings:

Fig. 1 is a more or less diagrammatic sectional view of a mechanism embodying the principles of the invention; and

Fig. 2 is a fragmentary section on larger scale showing another form of motion transmitting element incorporated in the organization shown in Fig. 1.

Referring now to Fig. 1, l0 denotes a continuously rotating shaft, while M denotes a shaft which is to be adjusted. On the shaft 10 there is mounted a pinion I2, which, however, isrmade' in such a manner that the'te'eth in the longitudinal space l3 have been milled off. The pinion I2 meshes with a second pinion, which does not l0. Claims. (01. 74.750)

appear in the drawing, since it lies behind the pinion 12. The secondpinion is made in such a way that the teeth are milled off at a portion corresponding to the portion l3 which, however, is situated. to the right in the figure. The pinion l 2 and the second pinion will consequently rotate in opposite directions. The pinion l2 meshes with a disc M, while the second pinion. correspondingly meshes with a disc I5. As the shaft rotates, the discs [4 and l5 will thus rotate with equal Velocity in opposite directions. These iscs ar mounted to turn freely onthe driven shaft H;

' In the most uncomplicated embodiment of the invention a number of holes are bored through each of the discs' M and I5 and in each such ,hole there is disposed a ball l6 and I1 respectively. The discs l4 and may be considered as retainers for the balls it and H in an axial thrust ball bearing. For very large couplings one even could put in complete ball bearings instead of each one of th separate balls l6 and i7; posed: a bearing disc EB' keyed to the shaft I Preferably the bearing disc is provided with two races t9 and in contact with the balls l6 and if respectively. A couple of corresponding races 2! and 22 are mounted in a fixed part of the device,.which part in this instance consists of the two casing halves 23 and 24 conveniently joined by bolts. In these halves are also mounted the ball bearings 25 and 25 for the shaft it and 21 and 28 for the shaft II. To each casing half 23 and 24 there is in addition attached a torusshaped magnetic core, shown at 29 and 38 respectively. the magnetic core 29 and in the torus-shaped opening 32 of themagnetic core the windings of ,these electro-magnets are'disposed. The magnets 29 and 3i] cooperate withthe disc-shaped armatures 33 and 34, which are keyed to the shaft ll. I

, The gearing according to the invention functions. in the following manner: It is assumed that in the customary manner thereis a very small clearance for axial motion inthe two radialball bearings 2'! and 28. The shaft II is thus able to move axially a trifling distance, in the order of magnitude of some tenth of a millimeter orpossibly even less.

The discs M and i5 rotate in opposite directions in the manner described above, when the continuously rotating shaft H! is kept moving. In this way the balls 16 and I! will thus rotate between theitwo' races; l9, 2i and 20, 22 respece Between the discs I4 and I5 there is dis- In the torus-shaped opening 3! of tively. There is reason to presume that between the balls and their respective races an oil film develops and in practice it has also turned out that in spite of the rotation of the discs l4 and I5 the disc 18 is not moved and that the friction between the moving discs I l and I5 and the stationary disc I8 is extremely small.

When the shaft I I is to be put in motion in one direction, current is supplied to the magnetic winding in the groove 3| so that the magnet becomes operative. It will then attract the armature 33 towards its poles and the shaft II will be displaced a very short distance, which, nevertheless, is sufficient for breaking the oil films between the balls I? and the races 20 and 22 so that the balls will make metallic contact with the races 2!] and 22. tween the balls H and the races 20, 22 increases abruptly and the disc 18 will consequently be rotated with a high rate of acceleration in the di'rection'of rotation of the disc 15. The shaft II is therefore put in motion practically immediately. If current had been fed to the winding in the groove 32 instead, so that the magnet 3% had attracted its armature 34, a corresponding contact would have been produced between the balls [6 and the races 19 and 2| and the shaft l i would have been rotated in the opposite direction.

Although the device according to the invention has been described above on the basis of the hypothetical assumption that an oil film is developed between the balls and their respective ra'ces; practical test has shown that in any case the device'has the effect which has been stated above even if the theory for explaining this effect might not be quite correct. therefore not dependent on said theory, but refers to the structure of the gearing device. This can be modified within the scope of the inventive idea and in so doing the different elements contained therein may have another shape or function than what has been stated above with reference to the embodiment just described.

As previously noted rollers may be used instead of balls and in Fig 2 such an arrangement is shown, in which rollers Mia and Ila are employed. As shown, these rollers should be conical so that the proper angular velocity is maintained at every point of the surface of the rollers. This is accomplished by making the taper of the rollers such that the apex of the conical envelope lies at the axis of rotation of shaft 1 I.

In the embodiments described the discs are shown as normal to the axis of rotation but they may be of different form to provide motion transmitting contact between conical surfaces, between which higher contact pressure may be obtained by application of a given engaging force, with correspondingly longer engaging movement and time. Also, while in the examples shown the balls or rollers are rotated and engage a stationary race, the reverse of thi arrangement will give an equivalent result. Obviously, so far as the functioning of thedevice is concerned, the shaft H may be the driving shaft and shaft Iii the driven;

It will therefore be understood that the invention is not restricted to the exampleshereinbefore described but includes all forms of appartaus falling within the scope of the appended claims.

What is claimed is:

ll A releasable friction gearing for transmitting motion between a uni-directional first shaft and a reversible second shaft comprising a first The invention is Now the friction be- 4 motion transmitting mechanism for connecting said shafts to cause them to rotate in the same direction, a second motion transmitting mechanism for connecting said shafts to cause them to rotate in opposite directions, each of said mechanisms including a releasable force transmitting device" having confronting race elements mounted for relative rotation with respect to each other and a plurality of rolling force transmitting elements disposed between said race elements certain of said race elements being connected to said second shaft, and means for selectively exerting compressive pressure on the rolling elements of one or the other of said devices to constrain the force transmiting elements of the device to simultaneously engage both of the races of the device in rolling contact and impart to the same a relative rotational movement resulting from'said rolling contact.

2. A gearing as set forth in claim 1, in which the compressive pressure for producing the rolling action of one or the other of said devices is provided by means for moving one of said shafts axially in one or another of two opposite directions.

3. A gearing as set forth in claim 1, in which one of the elements of each of said force transmitting devices is connected to one of said shafts, the connections being such that the directions of motion between the said one of said shafts and one of the connected elements are the same while the directions of motion between the said oneof said shafts and the other element connected to it are opposite.

4. A gearinga's set forth in claim 3, in which the elements connected to the said one of said shafts consist of carriers for the rolling force transmitting elements contacting said race ele-' ments.

5. A gearing as set forth in claim 1, including a rotationally stationary casing structure to which one of the race elements of each of said device is connected, and disc elements by which the rolling elements of each of said devices are carried operatively connected to rotate with one of said shafts and the remaining race elements of each of said devices are connected to the other of said shafts. 6. A gearing asset forth in claim 5, in which including means for moving one of said shafts axially to exert compressive force on the rolling elements of one or the other of said devices.

'7. A gearing as set forth in claim 1, in which the means for selectively exerting engaging pressure on said devices consists of an axially movable member arranged to move the confronting races of said devices toward or away from each other, and electromagnetic means for moving said member in selected direction.

8. A gearing as set forth in claim 7, in which the axially movable member comprises one of said shafts, radial ball bearings rotatably mounting said shaft, said bearings having sufficient play to permit limited axial movement of the shaft.

9. A gearing as set forth in claim 1, in which the elements in rolling contact with the races are balls.

10. A gearing as set forth in claim 1, in which the elements in rolling contact with the races are rollers.

CARL-ERIK GRANQVIST.

(References on following page) REFERENCES CITED Number Name Date The following references are of record in the 2,113,456 Stephenson A101" 5, 1933 file of patent: NOV. 29, s PATENTS 2,253,535 Weimg Aug. 26, 1941 UNITED STATE 5 FOREIGN PATENTS Number Name Date 272,988 Thompson Feb. 27, 1883 Number Country Date 745 814 Gibbs Dec, 1, 1903 20,897 France Ju y 23, 1919 1 765 59 t m July 1, 1930 204,512 Great Brl ln Nov. 16, 1923 2,081,824 Lambert May 25, 1937 10 769,261 France pr. 23, 1934 Certificate of Correction Patent No. 2,524,905 October 10,1950

CARL-ERIK GRANQVIST It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 6, list of references cited, under the heading UNITED STATES PATENTS add the following:

2,086 498 Geld/E0 Jul 6,1937

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Oifice.

Signed and sealed this 26th day of December, A. D. 1950.

[SEAL] THOMAS E MURPHY,

Assistant Gammissz'oner of Patents. 

